An apparatus comprises magnetic recording disk surfaces and magnetic recording heads comprising a leading and a following head. A controller moves the heads so that the leading head, at a passive fly height, follows a first track of a first disk surface containing a passive thermal asperity (PTA), and the following head, at a passive fly height, follows a first track of a second disk surface. The PTAs on tracks of the second disk surface define virtual PTAs on corresponding tracks of the first disk surface. The controller moves the heads away from the respective first tracks and to neighboring tracks to avoid the PTA and virtual PTAs. The controller is configured to move the heads back to the respective first tracks so that a write or read operation can be performed by the leading head.

According to one embodiment, a VCM resistance estimation unit estimates a VCM resistance in a voice coil motor based on an acceleration and a velocity of a magnetic head with a VCM voltage saturated, and an equivalent current force constant estimation unit estimates an equivalent current force constant of the voice coil motor based on the acceleration and the velocity of the magnetic head with the VCM voltage saturated.

In one general embodiment, an apparatus includes a first outer module having an array of writers, a second outer module having an array of writers, an inner module positioned between the outer modules, and a first actuator for shifting the first outer module. The shifting is relative to the inner module, in a cross-track direction by about one half of a center-to-center pitch of the writers of the first outer module. The inner module has an array of readers.

According to one embodiment, a position detecting device includes a detecting portion which periodically detects a plurality of pieces of information generated in accordance with positional information divided into upper digits and lower digits. The upper digits are further divided into a plurality of pieces of upper digit information equal to the number of the period. The pieces of the upper digit information are obtained in a predetermined order. The lower digits are obtained simultaneously with any one of the pieces of the upper digit information. The positional information is divided so that the number of values, which are obtainable in one piece of the upper digit information provided by dividing the upper digits, and a division number of the upper digits are coprime.

A driver device coupled to a winding of an electro-mechanical actuator includes: a power stage driving the winding in a discontinuous mode by alternating conduction on-phases to off-phases, and a sensor circuit sensing a voltage across the winding in an off-phase, wherein, during such an off-phase the voltage across the winding includes a residual voltage which decays to zero. The power stage drives the winding from an on-phase to an off-phase by applying to the winding a reverse current pulse to invert the direction of flow of the current through the winding and produce an oscillation of the residual voltage, whereby the residual voltage includes a zero-crossing point after the current through the winding is exhausted. The sensor circuit senses the voltage across the winding at this zero-crossing point, whereby the voltage sensed across the winding at the zero-crossing point is indicative of the back electromotive force of the winding.

A data storage device is disclosed wherein multiple voice coil motors (VCMs) are unloaded using a back electromotive force (BEMF) voltage generated by a spindle motor. A velocity and position of each VCM is measured, and a priority assigned to each VCM based on the measured velocity and position. During a delay interval, the BEMF voltage is used to apply a first brake voltage to a high priority VCM and to apply a second brake voltage to a low priority VCM, wherein the second brake voltage is lower than the first brake voltage. After the delay interval, the BEMF voltage is used to apply the first brake voltage to the high priority VCM and to apply a third brake voltage to the low priority VCM, wherein the third brake voltage is higher than the second brake voltage.

A tape drive device includes a head member, a tape drive mechanism moving a tape, a suspension member supporting the head member, piezoelectric units, a drive voltage supply circuit applying a voltage to a piezoelectric element, and a controller. Each of the piezoelectric units includes a piezoelectric element. The controller determines a state of a head unit, based on a piezoelectric output generated at the piezoelectric element provided in the suspension member.

A servo reproduction apparatus according to the present technology includes: a servo reproduction head. The servo reproduction head includes a first reproduction head portion and a second reproduction head portion. The first reproduction head portion reads a servo pattern recorded on a plurality of first servo bands, which are some of a plurality of servo bands in a magnetic tape including the plurality of servo bands. The second reproduction head portion reads a servo pattern recorded on a plurality of second servo bands, which are others of the plurality of servo bands.

A head driving device includes an actuator assembly driving a head member in a width direction of tape. The head driving device includes a first end support beam, a second end support beam, a first skew driving piezoelectric unit, and a second skew driving piezoelectric unit. The first end support beam is arranged between a first end portion of the head member in a length direction and a base member. The second end support beam is arranged between a second end portion of the head member in the length direction and the base member. The first skew driving piezoelectric unit and the second skew driving piezoelectric unit drive the head member around the Z-axis.

A seek operation of a first actuator in a multi-actuator drive is modified, so that one or more disturbance-generating portions of the seek operation do not adversely affect operation of a second actuator in the drive. Radial motion of the aggressor actuator is controlled by limiting a slew rate of the first actuator during one or more portions of the seek operation to be less than or equal to a threshold value. Because slew rate of the first actuator is the rate of change of radial acceleration of the aggressor actuator with respect to time, limiting the slew rate of the first actuator prevents or reduces mechanical disturbances caused by jerk associated with motion of the first actuator.